Mold coating and method of pouring ingots



United States Patent 3,212,145 MQLD COATING AND METHOD OF P DURING INGOTS Harold D. Green, Irwin, Pm, assignor to United States Steel Corporation, a corporation of New Jersey No Drawing. Filed Apr. 12, 1963, Ser. No. 272,522 5 Claims. (Cl. 22-192) This invention relates to the pouring of ingots and to a novel composition for coating the interior of ingot molds prior to teeming molten metal thereinto. It has long been the practice to apply a coating to the interior of ingot molds to restrict the formation of scabs in the surfaces of the ingots as a result of the splashing of liquid metal against the mold walls during teeming. Tar is perhaps the material most widely used for this purpose but it is objectionable because of the large volume of smoke it produces when the molten metal comes into contact with it, as well as for other reasons. Many other coatings have been used for this purpose but they all have various disadvantages. In many instances the coating is such that oxygen will be introduced into the steel during the teeming operation, it may be difficult to strip the ingots from the mold and/or the ingot surface may be poor.

It is therefore an object of my invention to provide an ingot mold coating composition which is easy to apply, which prevents or restricts oxygen from being introduced into the steel during teeming, which results in improved ingot surface and enables the ingot to be stripped easily from the mold.

Another object is to provide a method of pouring steel ingots utilizing such a composition to obtain an ingot having an improved surface thereon.

These and other objects will be more apparent after referring to the following specification.

According to my invention I prepare a mixture of cryolite, hexachlorethane, molasses and water. Superior results are obtained when the cryolite amounts to between 41 and 44% of the composition, the hexachlorethane between 29 and 28%, the molasses between 13 and 12% and the remainder is substantially all water. One particular suitable composition includes 41% cryolite, 29% hexachlorethane, 13% molasses and 17% water. All percentages given are by weight.

After the composition has been prepared it is applied to the inside surface of the ingot mold when the mold is at a temperature between 100 and 800 F. This may be done by means of a brush in which case it is preferred to apply four separate coats. Also the coating may be sprayed on. It is preferred that the temperature be at least 250 F. so that the coating will dry in a short time. After the coating becomes dry the molten steel is teemed into the mold. At this time the composition gives off a dense deoxidizing atmosphere which prevents oxygen from being introduced into the steel.

Prior to my invention, when using conventional mold coatings the loss due to conditioning the surface of the ice ingots or slabs varied from approximately 4 to 4.5% whereas my invention has reduced this loss to approximately 3.2 to 3.4%.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations may be made without departing from the scope of the following claims.

I claim:

1. A mold coating composition comprising a mixture of 41 to 44% cryolite, 29 to 28% hexachlorethane, 13 to 12% molasses, and the remainder substantially all water, all percentages being by weight.

2. The method of pouring steel ingots which comprises preparing a mixture of between 41 and 44% by weight of cryolite, 29 to 28% by weight of hexachlorethane, 13 to 12% by weight of molasses and the remainder substantially all water, providing a warm ingot mold at a temperature between 250 F. and 800 F., coating the interior walls of the warm ingot mold with said mixture, and teeming liquid steel into said mold whereby a dense deoxidizing atmosphere is produced within said mold.

3. The method of pouring steel ingots which comprises preparing a mixture of between 41 to 44% by weight of cryolite, 29 to 28% by weight of hexachlorethane, 13 to 12% by weight of molasses and the remainder substantially all water, coating the interior walls of an ingot mold with said mixture, and teeming liquid steel into said mold.

4. A mold coating composition comprising a mixture consisting essentially of a major proportion of cryolite, a lesser but substantial proportion of hexachlorethane, a still lesser but substantial proportion of molasses, and the remainder substantially all water, said proportions being by weight.

5. The method of pouring steel ingots which comprises preparing a mixture consisting essentially of a major proportion of cryolite, a lesser but substantial proportion of hexachlorethane, a still lesser but substantial proportion of molasses and the remainder substantially all water, said proportions being by weight, coating the interior walls of an ingot mold with said mixture, and then teeming liquid steel into said mold.

References Cited by the Examiner UNITED STATES PATENTS 2,791,815 5/57 Kinnear 22-215 3,052,532 9/62 Stoddard et a1 22216.5 3,052,936 9/62 Hamilton 22-215 3,075,847 1/63 Henry 10638.22

FOREIGN PATENTS 606,948 8/48 Great Britain.

MARCUS U. LYONS, Primary Examiner.

MICHAEL V. BRINDISI, Examiner. 

4. A MOLD COATING COMPOSITION COMPRISING A MIXTURE CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF CRYOLITE, A LESSR BUT SUBSTANTIAL PROPORTION OF HEXACHLORETHANE, A STILL LESSER BUT SUBSTANTIAL PROPORTION OF MOLASSES, AND THE REMAINDER SUBSTANTIALLY ALL WATER, SAID PROPORTINS BEING BY WEIGHT. 